This invention relates to a device used in an electro-discharge machining apparatus for moving the electrode according to a given program; more particularly, it relates to a device that can easily be attached to a commercial electro-discharge machining apparatus as an attachment.
A commercial electro-discharge machining apparatus is equipped with a main shaft which has an electro-discharging electrode on its lower end. This electrode is driven by the main shaft axially with respect to a workpiece.
If the drive feed rate of the electrode is increased to increase machining speed, the work surface facing the electrode becomes coarse. To lessen the coarseness of the work surface to a desired level, another machining is carried out with an electrode of a larger size, or the first electrode is moved relative to the workpiece in a direction substantially normal to its axis (or alternatively, the workpiece may be moved with the electrode being fixed). Conventionally, the former method is called "rough machining," and the latter "finish machining," and the process for moving the electrode transversely of and relative to the workpiece or the worktable in "finish machining" is called "approach machining."
In the prior art, approach machining is accomplished by the operator who empirically moves the workpiece-carrying work-table transversely of the electrode. Accordingly, the conventional approach machining largely depends upon the operator's dexterity, and is unfit for achieving high precision machining. Another defect of the conventional approach machining is that it is not efficient for providing complicated work patterns.